Production of acetylene



Feb. 2l, 1950 J, B, QRR, JR 2,498,444

l PRODUCTION oF ACETYLENE Filed Feb. 24, 1948 2 Sheets-Sheet 1 INVENTOR Feb. 21, 1950 J. B. oRR, JR 2,498,444

PRODUCTION OF ACETYLENE Filed Feb. 24, 1948 2 Sheets-Sheet 2 INVENTOR Patented Feb. 2l, 1950 UNITED STATES PATENT OFFICE PRODUCTIOICETYLIQE l John B. Orr, Jr., Great Barrington, Mass.

Application February 24, 1948, Serial No. 10,514

24 Claims. l

One phase of this invention pertains to the processing of natural gas for the production of unsaturated hydrocarbon compounds, more especially acetylene, and to lesser extent ethylene and other compounds of the ethylene series. In another sense, it pertains to the endothermal conversion of saturated reaction hydrocarbons of the methane series into unsaturated aliphatic hydrocarbons.

This is a continuation-in-part of my cepending application Serial No. 556,416 of September 29, 1944, entitled Apparatus and procedure for converting hydrocarbons to acetylene, which has been abandoned in favor of the present application.

The increased demand for starting materials for the plastic and synthetic rubber industry has developed an increasing need for unsaturated c-ompounds of this class, and attention has heretofore been given to the possibility of using natural gas for this purpose.- In certain regions large amounts of natural gas are available, butl in most cases such regions are remote from the industrial centers where acetylene is required. Processes heretofore proposed for preparing acctylene from natural gas have, in addition to certain vtechnical difficulties, given such a low yield of acetylene that even with extremely low cost of natural gas, the cost of producing the acetylene, plus the cost of transporting it to the place where it is to be used has far exceeded the cost of acetylene prepared by the more conventional processes, as for example, by these-called carbide process. f

As is well known to those skilled in the art, natural gas is comprised essentially of methane, and the present invention provides a process which converts methane into acetylene to give a much higher yield of acetylene per unit of natural gas processed. Because of the higher yield of acetylene for each unit volume of gas treated, considerably more acetylene can be produced from a given amount of capital invested for equipment. The present invention therefore enables methane to be converted into acetylene at a cost which, even considering greater transportation costs for the finished product, enables the acetylene to compete successfully with acetylene produced by the carbide process. In other words, the invention provides a cheaper or more elTective process for converting methane into acetylene than has been heretofore available, which is free of technical diiculties heretofore encountered and which enables acetylene to be produced from natural gas on a commercially feasible basis.

Generally, the present invention consists in cracking methane obtained as natural gas to acetylene by contacting such gas with a stream of combustion gases, the temperature of which 2 ranges between 1500 C. and 2000 Cl', reducing the temperature of the reducing mixture of methane and treating the resulting mixture between 900 C. and 1200o C. and maintaining them at this temperature for a period of time less than one second whilefpreferably, though not necessarily, continuing combustion in the combustion gases after the mixture has been effected.

More specifically, a mixture of air and natural gas consisting of amounts of each sufficient for complete stoichiometric combustion is partially burnt While traveling at high velocity through a refractory re wall. The temperature of the gases issuing from this combustion chamber is carefully controlled by controlling the amount of combustion taking place therein. This is dependent upon the velocity of the gases, the size of the chamber, and the area of the iire wall. By allowing 81% combustion to take place the temperature issuing from the combustion chamber is approximately 17C0 C.v

On issuing from the combustion chamber the gases enter an additional refractory chamber or cracking chamber. Upon entering the cracking chamber the hot gases are intimately mixed with natural gas in proportions of approximately ten volumes of hot gases to one of natural gas. The temperature of the resulting mixture is very quickly reduced to approximately 1000 C. lThe remaining oxygen inthe gas mixture is consumed by additional oxidation and the methane in the natural gas is substantially converted to acetylene, hydrogen, carbon, and carbon dioxide. The process time in the cracking chamberis'approximately one-tenth of a secon-d. On issuing, the gases are cooled immediately to prevent further reactions. The cooled and processed gases contain 1.6% acetylene. Extraction of the combustion gases leaves a gaseous mixture containing 10.8% acetylene, 68% hydrogen, and 21.2% unreacted methane. (The above percentages are per cent by volume in each instance.)

The accompanying drawings illustrate various types of apparatus in which the present invention may be practiced. In the drawings: j

Figure 1 is a longitudinal sectional elevation taken through a crackingapparatus employed in operating the process of the present invention;

Figure 2 is a transverse sectional elevation taken along the line II-II of Figure l; l

Figure 3 is a fragmentary longitudinal sectional elevation of a modified form ofjapparatus;

Figure 4 is a section similar to Figure Zbut showing a modified arrangement;

Figure 5 is a fragmentary sectional elevatio of a still further modiiied form of the apparatus;

Figure 6 is an enlarged fragmentaryelevation of an element of the apparatus of Figure 5;..and

-Figure 7 is a transverse sectional elevation taken also along the section line II-II of Figure v l l, looking in the direction of the arrows, and

`a controlled combustion of the said mixture through a surface combustion phenomenon, the volume of the combustible gas-air mixture and the area of the fire-wall I3 being proportioned so as to produce, preferably, only a partial combustion of the said mixture, for example, the eighty-one per cent combustion referred to above. This is so that a temperature of approximately l700 C. is obtained in the combustion zone, which is that portion within the tube between the nre-wall I3 and the plane of the intake pipe l5 for admission of the gas to be cracked. As shown, the gas to be cracked is introduced at right angles, laterally or transversely, to the stream of burning combustible mixture but it may be introduced in the same direction.

The burning mixture impinges on the gas to be cracked at a temperature of approximately 1700 C., the resulting mixture having a temperature of from 900 C. to 1200" C. I

The cracking zone extends from the plane of the gas intake pipe l5 to the outlet end of the tube I0. In this zone, the remaining oxygen present in the combustible mixture, which has been only partially burned, as explained above,

is consumed and the methane in the gas being cracked is converted to a substantial extent into 4 acetylene, hydrogen, carbon, and carbon dioxide,

any CO will be of smaller quantity than the CO2.

The following example illustrates a preferred method in determining the amount of combustion taking place in any particular portion of the reaction tube I0. The burning of a combustible fluid such as natural gas and air, or the oxygen content thereof, is a chemical reaction involving the formation of different gaseous products such as steam and carbon dioxide, carbon monoxide, hydrogen, etc., when, for example, the natural gas contains a substantial portion of methane. Heat is produced by the chemical reaction. Taking volumes of the gases as one cubic foot equal to unity, the following chemical equation is illustrated:

When all the available oxygen which is free or capable of being easily freed, has been consumed and none of the resulting products of combustion are capable of further combustion reactions, the above example illustrates complete combustion. The amount of heat released is said to be the total amount produced by complete combustion in the sense of utilization of all available oxygen. If less than the above amount of heat were released in the combustion of a mixture of air and methane, the reaction would be termed incomplete, since further heat can be released by further combustion reactions. It is thus possible to determine exactly how far a certain combustion reaction has proceeded by calculating how much heat has been released by the reaction. If, for example, in a certain combustion 'reaction it was determined that 449 B. t. u. of heat is released per cubic foot of entering methane, the combustion reaction would have been 50% complete.

The calculations necessary to determine the amount of heat released are relatively simple to those skilled in the art. Any good reference book on heat and combustion covers the subject adequately, see The Chemical Engineers Handbook, 1941 edition. In the examples given in this specification, the following calculations may be used to determine the percentage of combustion:

(l) Temperature of entering gases ll00 C.=20l0 F.

Temperature of gases issuing from combustion zone 1700 C.=3090 F.

Temperature difference 600 C. l080 F. Practically all the heat released will be utilized in increasing the temperature of the issuing gases. The speciiic heats of the issuing gases are as follows:

N2, Oz, CO, and Ha 0.020 B. t. u./cu. ft./l F. H2O 0.02G B. t. u./cu. ft./l F. C02 0.032 B. t. u./eu. it./l F.

(2) The approximate volumes of issuing gases per hour times the specic heat is:

Heat consumed as above times total temperature increase:

60.82 B. t. u./hr./l F.X1080 F.=65,700 B. t. u./hr.

(total heat put in gas mixture) Total heat released if combustion had been complete:

(3) 120 cu. It./hr. X898 B. t. u.Xl08,000 B. t. u./hr. Percentage of complete combustion:

65,700 B. t. u.

108.000 B. t. u. 603% It will be noted with reference to (l) above, that the temperature of the entering gases is indicated as being 1100 C. That is, as shown in the examples hereinafter set forth and by the embodiment of Figure 5 of the drawings, it is advisable to preheat the combustion gases entering the reaction tube to minimize the combustion heat energy required for obtaining the desired temperature ranges within the reaction tube. As to (2) above, these volumes are based on an actual measurement of the gas leaving the exhaust or outlet end of the reaction tube as analyzed chemically, for example, to determine the amount and type of each issuing gas of the mixture; that is, any conventional method, such as the Orsat low temperature fractional distillation analysis method may be employed. The 120 cu. ft./hr. volume of item (3) in this example represents the volume of the combustible methane gas which is introduced into the inlet end of the reaction tube. The increased output volume is due to the reaction hydrocarbons that are being cracked and to the air used for carrying out combustion.

vSimilar calculations were made in the other examples given in this specification to determine the amounts of combustion which took place. In short, the amount of combustion taking place is determined by a heat balance calculation.

Since it is a simple matter to utilizevwellknown equipment to determine the exact gases issuing from a particular portion of the reaction tube I0 as well as the temperature of those gases at any point in the chamber, determination of the percentage of combustion can be made as above indicated. That is, a desired heat balance in the combustion and reaction portions of the reaction tube I can be provided for any given set of conditions. That is, the temperature, volume, and velocity of the gases, the amount of the gases, and the size of the combustion and reaction zones and area of fire walls can be adjusted to provide the desired percentages of the combustion in the combustion and reaction portions of the zone formed by the reaction tube;

and an actual determination of whether or not the desired percentages of combustion are being eifected can be made as above outlined.

From a practical standpoint; I maintain desired heat balance conditions in the upstream or main combustion zones or portions of the reaction tube length ID such that the combustion is from 50% to 85% complete to the extent of the available oxygen content thereof, e. g., I burn 50% to 85% of such oxygen content. After such combustion gases enter the downstream portions of the tube I0 and are partially cooled by and mixed with the entering reaction hydrocarbons, I maintain suitable heat balance conditions therein such that the remaining available oxygen content of the mixed gases is consumed, or in other words, combustion is continued to the extent of 50% to 15% of the original oxygen content of the combustion gases. The type of gases issuing from the outlet of the reaction tube I0 will thus indicate whether the combustion of the available oxygen content has been completed or not, if not the heat balance conditions are adjusted accordingly. Although additional oxygen may be introduced after the initial combustion, I prefer to utilize the original content of the combustion gases. Of course, such heat balance relationships take into consideration the critical temperature bases set forth herein for the production of acetylene. The invention makes possible a continuous process of high efciency for producing acetylene from natural gases or from those containing saturated hydrocarbons of the methane series, see page 5, line 10 of my application No. 404,460, now abandoned, of which my application No. 556,416 is a continuation-in-part.

As shown in the drawings, the combustible gases having a suitable available air oxygen content are introduced lengthwise through the one end of the reaction tube and sweep or now through the upstream portion of such tube aS dened primarily by the flow-restricting refractory portions I3 into the downstream mixing and reaction portion I6 of the tube I0 as defined primarily by an inlet opening such as I through which the reaction hydrocarbon uids are introduced. The laterally positioned refractory flowrestricting portions I3 dene the main combustion chamber or upstream zone and the inlet opening I5 for the reaction gases defines the downstream mixing and reaction zone through one end of which the mixed gases exhaust lengthwise thereof. Although I prefer the utilization of gases, it is apparent that vapors may also be reacted in accordance with my invention. Thus, in referring to gases I include suitable vapors. Combustion is preferably effected in the upstream portion of the enclosed reaction zone or zones to the extent of burning a portion of the oxygen content of the combustion gases and in the downstream portion to substantially the full extent of the remaining oxygen content of the mixed gases; by maintaining a suitable heat balance in the upstream and downstream portions, combustion is controlled; and, optimum results for the production of acetylene are obtained by maintaining suitable temperatures in such zones or upstream and downstream portions.

In the embodiment shown in Figure 5, the air being introduced through tube length 28 moves in a continuous later, circular, or spiral path about the upstream or main combustion portion ofthe reaction tube 20 in such a manner as to impart heat to the entering air through the walls of the reaction tube 20. In this manner the upstream portion of the reaction tube may be cooled while at the same time pre-heating the entering air.

The lengthwise sweep of the gases or fluids through lengthwise connected portions or zones of the reaction tube of my invention keeps the inside of the reaction tube clean from carbon and tar deposits and thus further insures a continuous process. That is, the sweep is lengthwise from the inlet at the upstream end of the reaction tube through an outlet at the downstream end thereof which extends lengthwise through such downstream end. The location of the refractory portions as above intimated in effect defines the extent of the main combustion chamber and makes control of the combustion process a simple matter.

The reacted gases pass through outlet pipe II to a water condenser and stripping plant. As the reacted gases issue from the reaction tube I8, they may be cooled immediately by a stream quench entering the pipe II through pipe I0.

The use of the fire wall I3 is essential to the operation of the present process. It initiates the combustion of the highly preheated gas-air combustible mixture by condensation thereof on its surfaces and surface combustion thereof. It brings about an intimate mixture between the gas and air. It controls the amount of combustion, and the resulting temperature of the partially burned mixture. If the temperature of the partially burned mixture substantially exceeds l700 C., there is a likelihood that the molecular collisions between the mixture and gas being cracked will cause excessive cracking of the latter to carbon, with consequent reduction of the desired acetylene. It is not possible to obtain the desired temperature control and combustion control without the use of the fire wall.

As has been mentioned above, it is preferred to operate with a combustion that is substantially incomplete, since it is found that substantially lower yields of acetylene are obtained when combustion of the combustible mixture reaches completion before mingling with the gas being cracked. This is shown by the following example:

A mixture of air and steam was preheated to approximately 1100 C. Natural gas was mixed with this mixture in the combustion zone of the tube I0, the amounts of air and natural gas being such that complete combustion took place in the combustion zone Without additional oxy-v gen, natural gas, hydrogen, or carbon monoxide cracking zone and mixed with natural gas which is cracked thereby.

This example differs from the preceding and the following examples in that there is no oxidation in the cracking zone. After cooling and extraction of burned gases and steam, the remaining gases were found to contain 7.6%' acetylene, 40% hydrogen and 52.4% unreacted methane. This compared with a content of 10.8% acetylene in the example given above Where there Wasa combustion of only 81% completion in the completion in the combustion zone.

These yields represent typical yields obtained in practice, and Where the combustion is complete in the combustion zone, the yields of vacetylene are found in practice to be always substantially less than where the combustion is incomplete in the said combustion zone.

The following example employs steam as a diluent of the combustion mixture for obtaining additional temperature control, there being incomplete combustion of the combustibe mixture. The example is also illustrative of size of the apparatus and other operating conditions.

In accordance with this example, air and steam were preheated to approximately 1100 C., and were in approximately equal proportions by volume. Sufficient natural gas was mixed therewith to give a stoichiometric ratio. Burning took place in the combustion chamber, but the velocity of burning gases and steam, the size of the combustion zone and the area of the fire wall were such that only 60% combustion took place therein. The temperature of the gases issuing from the combustion zone was approximately 1700 C., this being the temperature at which the said gases enter the cracking zone. On entering the crack' ing zone, the hot, partially burned gases and steam are mixed with natural gas in proportion of approximately one part of natural gas to seven parts hot gases (parts by volume). Oxidation takes place therein until all the remaining unconsumed oxygen in the combustion mixture is consumed. The temperature in the cracking zone was approximately 1000 C. and the residence time in the cracking zone was approximately one-tenth second. The cooled gases contained 3% acetylene, and after condensation of steam from the reaction gases, and after extraction of products of combustion, the nal gaseous product was found to consist of 11% acetylene, 68% hydrogen, and 21% unreacted methane. In the foregoing, the following values may be noted as having been maintained during this last example:

Length of reaction tube 60 inches Inside diameter ol reaction tube 4-inches Composition of reaction tube Silicon carbide Fire wall Five silicon carbide tubes,

13e, Figure 7, three inches long, seven-eighths inches inside diameter, one and threeeighths inches outside diameter, arranged symmetrieally in the reextraction of wat-er, nitrogen, and carbon dioxide.

This 11% yield ef acetylene produced wit 60% combustion in the combustion zone. demonstrates further the increased yields of acetylene resulting from incomplete combustion in the combustion zone.

In the second example above, there was complete combustion in the combustion zone, with no combustion in the cracking zone, and the yield of acetylene was 7.6%. In the first and third examples, there was combustion in the cracking zone, with incomplete combustion in the combustion zone, and the yield of acetylene was 10.8% and 11.0% respectively.

A fourth example now is given to illustrate what happens when the temperature of the hot gases is substantially greater lthan 1700" C., and there is no oxidation in the cracking zone, combustion being complete in the combustion zone.

In accordance with the fourth example, equal parts of air and steam were preheated to 1100 C. Natural gas was mixed therewith suicient to give a stoichiometric mixture. The velocity of the gases going through the combustion chamber, the size of the chamber, and the area of the fire wall were such as to give complete combustion therein. The temperature of the hot gases issuing from the combustionzone was approximately 2000 C. Natural gas was mixed with the hot gases in the cracking chamber in the approximate proportions of one to seven. After cooling and extraction of the burned gases, the remaining gaseous mixture consisted of only 4.3 acetylene, '74% hydrogen, and 21.7% methane.

From the foregoing example there is demonstarted a factor which is unknown to the prior art, that is, the injurious effects of too high combustion temperatures and lack of combustion in the downstream or reaction zone.

An important features of novelty in the present invention lies in the recognition of such injurious effects, and the control of temperature and combustion conditions to obviate such injurious effects, as has been indicated above.

Reference now may be had to the apparatus modifications illustarted in Figures 3 through 6.

In the modification shown in Figure 3, the air and gas are introduced through inlet Il into a centrally positioned combustion chamber I2a, while a superheated diluent fluid, such as steam or carbon dioxide, for example, is introduced throughy portions I9 of the same end of the tube l0a on either side of the combustion chamber 12a. As will be noted, the steam will be heated by the combustion in chamber 12a before it reaches the cracking chamber I6. The other parts of the device are substantially the same as those shown in the arrangement of Figures l and 2.

Referring particularly to Figures 5 and 6, the combustible fluid is introduced into the combustion chamber 24 through inlets 2l and 22, Air employed for combustion purposes, which may be relatively cold, is introduced through the inlet 28 and moves about spiral passages provided by the spiral vanes 26, to exhaust as hot or preheated air through pipe 23 and inlet 22 into the combustion chamber 24. The fire Wallis represented by 25 which separates the mixing zone from the combustion zone 29.

It will be apparent that the entering air moves backwardly about the refractory tube 20 and is heated through wall portions thereof before it enters the front end with the fuel. Methane to be cracked is introduced through inlet 21. Brickwork for retaining heat is indicated by numeral 30.

AFigure 4 shows a four-bladed fan-shaped form of fire wall |317, which may be employed for the 9 fire wall I3 of Figure 1. The entering gases upon hitting the iire wall are burned, as previously described.

It will be apparent to those skilled in the art that many combinations of combustion gases and inert gases may be employed, and many variations of combustion chamber sizes and gas velocities and design of fire wall may be used which will limit the temperature of the hot gases issuing from the combustion chamber and result in some oxidation in the cracking chamber. Therefore, it is not desired to limit the invention through specifying certain quantities of air, natural gas, and steam for combustion purposes, nor specic sizes or design of the combustion and cracking chamber or zones, and fire wall.

In practice, combustions as low as 50% complete in the combustion zone have been employed successfully. On the high side, it is not advisable to operate above approximately 85% completion for maximum yields. While a temperature of approximately 1700 C. is preferred at the entrance of the cracking zone,l this is not an invariable quantity, since controlled conditions of velocities and temperatures that will produce reaction temperatures of from approximately 900 C. to approximately 1200 C., with a reaction time of less than one second, produce good yields of acetylene with an incomplete combustion in the combustion zone within the range above indicated.

Similar procedure can be employed for cracking homologues of methane, but such application of the procedure will, to some extent, from a practical standpoint, be determined by the cost involved, which tends to increase with succeeding higher members of the methane series. The present process is substantially more favorable, economically, than the carbide process. claims where stoichiometric amount is mentioned, I have reference to the amount of oxygen required to complete combustion from the standpoint of the available combustible content of the gases involved.

The operations may be controlled to produce ethylene rather than acetylene, the only different factor being to operate at still lower temperatures than those specied herein.

When, as pointed out herein, the combustionsupporting oxygen-containing gas is supplied to the upstream zone in substantially stoichiometric amounts for complete combustion, it will be apparent that after partial combustion in the upstream zone, the amount of combustion-supporting oxygen-containing gas in the downstream zone will be substantially less than of stoichiometric amount. Moreover, I desire to substantially consume all of the remaining available combustion-supportingr oxygen in the oxygen-containing gas in the downstream zone by continuing the combustion therein. This is also true when some combustion-supporting oxygen-containing gas is introduced along with the reaction hydrocarbons as a reaction gas through the inlet I5, see Figure l of the drawings. When speaking of oxygen-containing gas, I have reference to oxygen, itself, air, or any gas containing oxygen that is available for supporting combustion. And when speaking of the stoichiometric amount of such a gas for supporting combustion, I have reference to the available combustionsupporting oxygen content thereof. It is important in carrying out my invention to maintain proper heat balance conditions both in the upstream and downs ream connected zones in such a manner as toeie'ct combustion in the upstream zone, to continue combustion during the passage of the combustion gas mixture into the downlstream zone, and to complete combustion after consumed. As pointed out herein, my present In the procedure applies particularly to the production of unsaturated hydrocarbons comprising essentially acetylene and to a lesser extent gases of the ethylene series. That is, the hydrocarbons to be produced are of the aliphatic type as distinguished from the aromatic type, but it is felt that my broad teachingsl as to a two-step procedure may be applied to other compounds, such as those of the aromaticand other types.

Although I prefer to utilize inexpensive hydrocarbons such as those contained in natural gas in eiecting combustion, it will be apparent that hydrogen, itself, may be employed, see Examples D and E of page 8 of my application Serial No. 404,460 filed July 29, 1941, now abandoned, and entitled Apparatus and procedure for converting hydrocarbons to acetylene. That is, broadly speaking, any suitable combustible hydrogencontaining gas may be employed with a combustion-supporting oxygen-containing gas to provide the combustible gas mixture. But, as above intimated, I prefer toemploy a hydrogen-containing gas which also contains carbon in combination therewith, such as represented by methane, for example. Best results are obtained when the combustion-supporting gas used has an ainity for combustion with oxygen not less than that of the reaction gas later introduced. It is also believed that optimum results are obtained when such combustion-supporting gas is the same as the reaction gas used.

summarized Ibrieiiy, I have provided a two-step procedure wherein a preliminary or partial combustion is first effected and is continued while reaction hydrocarbons are being introduced. Completion of combustion from the standpoint of the available combustion-supporting oxygen content of the admixed gases which include the reaction hydrocarbons is then subsequently effected and completed as a continuation of the preliminary combustion. A second phase of the invention is believed to rest upon the discovery that extremely high temperatures are disadvantageous and that the maximum starting temperature should not be in excess of about 2000 C. Although it is believed that these two phases are of critical importance, it will be apparent that I have made further discoveries as to optimum and preferred operating conditions. The result is an inexpensive and exceptionally eiicient, high yield procedure.

What I claim is:

1. A method of endothermically producing unsaturated aliphatic hydrocarbons from gases containing saturated reaction hydrocarbons of the methane series which comprises, the steps of effecting combustion of a combustible gas mixture of a combustible hydrogen-containing gas and a combustion-supporting oxygen-containing gas at an elevated combustion-supporting temperature of not in excess of 2000 C., in such a manner that at least a portion of the combustible gas mixture is burnt and while segregating the combustible gas mixture from the surrounding atmosphere and moving it'as a continuous stream; introducing reaction gas directly into admixture with the ll combustible gas mixture downstream thereof, the admixed gases have substantially less than a stoichiometric amount of available combustionsupporting oxygen, and moving the admixed gases under conditions such as toinsure a continued and substantial completion of combustion of the therein available oxygen content of the admixed gases and under conditions such as to provide an elevated combustion-supporting temperature below that of the combustion-supporting temperature of the combustible gas mixture before the reaction hydrocarbons are introduced thereto and to provide an improved yield of unsaturated aliphatic hydrocarbons, while segregating the admixed gases from the surrounding atmosphere and converting saturated hydrocarbons of the admixed gases into unsaturated aliphatic hydrocarbons.

2. A method as defined in claim 1, wherein the reaction gas is introduced at a point where the elevated combustion-supporting temperature of the combustible gas mixture is about 1700 C.

3. A method as defined in claim 1 wherein, a superheated diluent uid is mixed with the portion of the combustion gas that is burnt in accordance with the first step of said claim.

4. A method of endothermically producing unsaturated aliphatic hydrocarbons from gases containing saturated reaction hydrocarbons of the methane series which comprises, the steps of ef- Afecting combustion of a combustible gas mixture of hydrocarbon gas a1 i an available combustionsupporting oxygen-containing gas at an elevated combustion-supporting temperature of not in excess of 2000 C., until a portion of the combustible gas mixture is burnt, and while segregating the combustible gas mixture from the surrounding atmosphere and moving it as a continuous stream; introducing reaction hydrocarbons directly into admixture with the partially burnt gas mixture downstream thereof, and moving the admixed gases under conditions such as to insure a continued and substantially completion of combustion ofthe therein available oxygen content of the admixed gases and under conditions such as to provide an elevated combustion-supporting temperature below that of the combustion-supporting temperature of the combustible gas mixture before the reaction hydrocarbons are introduced thereto and to provide an improved yield of unsaturated aliphatic hydrocarbons,whi1e segregating the admixed gases from the surrounding atmosphere and converting saturated hydrocarbons of the admixed gases into unsaturated aliphatic hydrocarbons.

5. A method as defined in claim 4, wherein the hydrocarbon gas ci?4 the combustion gas mixture has an ability for combustion with the available oxygen content of the admixed gases at least equal to that of the reaction hydrocarbons.

6. A method of endotherrnically producing unsaturated aliphatic hydrocarbons from gases containing saturated reaction hydrocarbons of the methane series Within a pair of connected and enclosed processing zones one of which is termed an upsrteam zone and the other of which is termed a downstream zone, the steps of introducing a combustion gas mixture of hydrocarbon gas and an available combustion-supporting oxygen-containing gas into the upstream zone, effecting combustion of the cobustion gas within the upstream zone at an elevated combustionsupporting temperature of not in excess of about 2000 C. by moving the gas, therethrough in amounts and at a velocity and under heat balance conditions such that a portion of the availvdrocarbons directly into the downstream zone and into admixture with the combustion gas therein, the mixed gases within the downstream zone having substantially less than a stoichiometric amount of combustion-supporting oxygen-containing gas, the reaction hydrocarbons andthe mixed gases being moved through the downstream zone in amounts and under heat balance conditions sufilcient to insure continued combustion and a substantial completion of combustion therein of the therein available oxygen content of the mixed gases and to endothermically convert saturated hydrocarbons of the mixed gases into unsaturated aliphatic hydrocarbons.

7. A method of endothermically producing unsaturated aliphatlc hydrocarbons of the class comprising acetylene and ethylene from gases containing saturated reaction hydrocarbons of the methane series within a pair of connected and enclosed processing zones one of which is termed an upstream zone and the other of which is termed a downstream zone, the steps of introducing a combustion gas mixture of hydrocarbon gas and an available combustion-supporting oxygen-containing gas into the upstream zone, effecting combustion of the combustion gas within the upstream zone at an elevated combustion-supporting temperature of not in excess of about 2000 C. by moving the gas therethrough in amounts and at a velocity and under heat balance conditions such that a portion of the available gas will be burnt, continuing to burn the combustion gas while introducing it into the downstream zone, and introducing reaction hydrocarbons directly into the downstream zone and into admixture with the combustion gas therein, the mixed gases within the downstream zone having substantially less than a stoichiometric amount of combustion-supporting oxygencontaining gas, the reaction hydrocarbons and the mixed gases being moved through the downstream zone in amounts and under heat balance conditions sufficient to insure continued combustion and a substantial completion of combustion therein of the therein available oxygen content of the mixed gases at a temperature of at least about 300 C. lower than the temperature of combustion in the upstream zone and to endothermically convert saturated hydrocarbons of the mixed gases into unsaturated aliphatic hydrocarbons;

8. A method of endothermically producing unsaturated aliphatic hydrocarbons of the class comprising acetylene and gases of the ethylene series from gases containing saturated hydrocarbons of the methane series within a pair of connected and enclosed zones one of which is termed an upstream zone and the other of which is termed a downstream zone, the steps of introducing a combustion gas mixture of saturated hydrocarbon gas and a gas having an available combustion-supporting oxygen content into the upstream zone. eiecting partial combustion of the combustion gas within the upstream zone at an elevated combustion-supporting temperature of not in excess of about 2000 C. by moving the gas therethrough in amounts and at a velocity and under heat balance conditions such Vthat only a portion of the available combustible gas content will be burnt, continuing to burn the combustion gas while introducing it into the downstream zone, introducing reaction hydrocarbons directly into the downstream zone and into admixture with the combustion gas therein, utilizing the available combustion-supporting oxygen gas content in the upstream and downstream zones in such a manner that the combined amount of the available combustion-supporting oxygen burnt in the zones in substantially stoichiometric with respect to the combustible gas content of the combustion gas mixture introduced into the upstream zone, and moving the admixed gases through the downstream zone in amounts and under heat balance conditions sulcient to insure a continued combustion and a substantial completion of combustion of the therein available oxygen gas content of the mixed gases to endothermically convert the saturated hydrocarbons into unsaturated aliphatic hydrocarbons.

9. A method of endothermically producing unsaturated hydrocarbons of the class comprising acetylene and gases of the ethylene series from gases containing saturated reaction hydrocarbons of the methane series within a pair of connected and enclosed zones one of which is termed an upstream zone and the other of which is termed a downstream zone, the steps of introducing a combustion gas mixture in substantial stoichiometric amounts for complete combustion into the upstream zone, the combustion gas mixture containing hydrocarbon gas and an available combustion supporting oxygen containing gas, burningr the combustion gas within the upstream zone at an elevated combustion-supporting temperature of not in excess of about 2000 C. by moving the gas therethrough in amounts and at a velocity and under heat balance conditions such that a portion of the available combustionsifpporting oxygen-containing gas will be burnt, continuing to burn the combustion gas while introducing it into the downstream zone, introducing reaction hydrocarbons of lower temperature than the combustion gas directly into the downstream zone and into admixture with the combustion gas within the downstream zone, the admixed gas being in amounts and at a temperature suiiicient to insure proper lower temperature heat balance conditions within the downstream Zone for continued combustion therein and for conversion of the reaction hydrocarbons into unsaturated hydrocarbons, the gas mixture within the downstream zone having substantially less than a stoichiometric amount of an available combustion supporting oxygen containing gas, and effecting a continuation of combustion within the downstream zone by moving the mixed gases therethrough in amounts and under heat balance conditions suicient to insure a substantial completion of burning of the available oxygen-containing gas content thereof and to endothermically convert saturated hydrocarbons of the methane series of the mixed gases into unsaturated hydrocarbons.

10. A' method of endothermically producing unsaturated hydrocarbons of the class comprising acetylene and gases of the ethylene series from gases containing saturated reaction hydrocarbons of the methane series within a pair of connected and enclosed zones one of which is termed an upstream zone and the other of which is termed a downstream zone, the steps of introducing a combustion gas mixture of hydrocarbon gas and an available combusion-supporting oxygen-containing gas into the upstream zone, at

least a portion of the gas content oi the combustlon gas being preheated, effecting combustion of the gas within the upstream zone at an elevated combustion-supporting temperature of not in excess of about 2000 C. by moving the gas therethrough in amounts and at a velocity and under heat balance conditions such that a portion of the available gas will be burnt, continuing to burn the gas While introducing it into the downstream zone, and introducing reaction hydrocarbons of lower temperature and of lesser amount than the combustion gas within the downstream zone directly into the downstream zone and into admixture with the gases therein, the gas mixture having substantially less than a stoichiometric amount of an available combustion-supporting oxygen-containing gas within the downstream zone, and the admixed gases being moved through tl-.e downstream zone in amounts and under heat balance conditions sufcient to insure continued combustion and a substantial completion of combustion of the therein available combustion-supporting oxygen-containing gas content and to endothermically convert saturated reaction hydrocarbons into unsaturated hydrocarbons.

11. A method as defined in claim 10, wherein the combustion gas mixture is introduced in the direction of the gas flow through the enclosed Zones and the reaction hydrocarbons are introduced substantially at right angles to the direction of the gas now through the enclosed zones into the downstream zone.

12. A method of endothermically producing unsaturated aliphatic hydrocarbons from gases containing saturated reaction hydrocarbons of the methane series within a pair of connected and enclosed zones one of which is termed an upstream zone and the other of which is termed a downstream zone, introducing a combustion gas mixture of hydrocarbon gas and an available combustion-supporting oxygen-containing gas into the upstream zone, effecting combustion of the gas within the upstream zone at a temperature of about 1500 to 2000 C. by moving the gas therethrough in amounts and at a velocity and under heat balance conditions such that a portion of the gas will be burnt, continuing to burn the combustion gas while introducing it into the downstream zone, introducing relatively cool reaction hydrocarbons directly into the downstream zone and into admixture with combustion gas Within the downstream zone, and effecting a substantial completion of combustion within the downstream Zone by moving the admixed gases therethrough in amounts and under heat balance conditions suiicient to insure continued combustion and a consumption of substantially all the therein available oxygen content of the mixed gases at a temperature of about 900 to 1200 C. and to endothermically convert saturated hydrocarbons of the mixed gases into unsaturated aliphatic hydrocarbons.

13. A method of endothermically producing unsaturated aliphatic hydrocarbons from gases containing saturated reaction hydrocarbons of the methane series which comprises, the steps of effecting combustion of a combustible gas mixture of a combustible hydrogen-containing gas and a combustion-supporting oxygen-containing gas at an elevated combustion-supporting temperature of not in excess of 2000 C., in such a manner that at least a portion of the available gas mixture is burnt, while segregating the combustible gas mixture from the surrounding atmosphere and moving it as a continuous stream, and effecting about 50% to 85% combustion of the combustible gas mixture before introducing reaction hydrocarbons thereto; introducing reaction hydrocarbons directly into admixture with the combustible gas mixture downstream thereof; eiecting 50% to 15% combustion based on the combustible gas content of the combustible gas mixture after the reaction hydrocarbons have admixed with the combustible gas mixture, and moving the admixed gases under conditions such as to insure a continued and substantial completion of combustion of the therein available oxygen content of the admixed gases and under conditions such as to provide an elevated combustion-supporting temperature below that of the combustion-supporting temperature of the combustible gas mixture before the reaction hydrocarbons vare introduced thereto and to provide an improved yield of unsaturated aliphatic hydrocarbons, while segregating the admixed gases from the surrounding atmosphere and converting saturated hydrocarbons of the admixed gases into unsaturated aliphatic hydrocarbons.

14. A method as set forth in claim 13, Wherein the elevated combustion-supporting temperature of the admixed gases is at least 300 C. below the elevated combustion-supporting temperature of the combustible gas mixture.

15. A method as dened in claim 13 wherein, a superheated diluent fluid is mixed with a portion of the combustion gas that is burnt in accordance with the first step of said claim.

16. A method of endothermically producing unsaturated aliphatic hydrocarbons and essentially acetylene from gases containing saturated reaction hydrocarbons of the methane series within a pair of connected and enclosed zones one of which is termed an uptream zone and the other of which is termed a downstream zone, the steps of introducing a combustion gas mixture of hydrocarbon gas and an available combustion-supporting oxygen-containing gas of sufficient amount to support at least about 50 %85% combustion into the upstream zone, effecting about 50% to 85% combustion of the combustible content of the combustion gas within the upstream zone at an elevated combustion-supporting temperature of not in excess of about 2000 C. by moving the gas therethrough in amounts and at a velocity and under heat balance conditions such 16 carbons of the mixed gases into unsaturated aliphatic hydrocarbons.

17. A method of endothermically producing uny saturated aliphatic hydrocarbons and essentially as to control combustion within the range above indicated, continuing to burn the combustion gas while introducing it into the downstream zone, introducing reaction hydrocarbons directly into the downstream zone and into admixture with the gas therein, effecting a continued and a substantial completion of combustion within the downstream zone to the extent of the therein available combustion-supporting oxygen-containing gas, the combustion-supporting oxygen gas within the downstream zone being'in sufcient amount to support 50% to 15% combustion based on the combustible content of the combustion gas introduced into the upstream zone, and moving the mixed gases through the downstream zone in amounts and under heat balance conditions suicient to insure the substantial completion of combustion of the therein available combustion-supporting oxygen-containing gas content of the mixed gases at an elevated combustion-supporting temperature of not in excess of about 1200 C. and to at the same time endothermically convert saturated hydroacetylene from gases containing saturated reaction hydrocarbons of the methane series within a pair of connected and enclosed zones one of which is termed an upstream zone and the other of which is termed a downstream zone, the steps of introducing a combustion gas mixture of hydrocarbon gas and an available combustion-supporting oxygen-containing gas into the upstream zone, effecting combustion of the combustion gas within the upstream zone at a temperature of about 1500 to 2000 C. by moving the gas therethrough in amounts and at a velocity and under heat balance conditions such that about 50% to 85% of the available oxygen gas content thereof will be burnt, continuing to burn the combustion gas while introducing it into the downstream zone, introducing saturated reaction hydrocarbons of lower temperature than the combustion gas directly into the downstream zone and into admixture with the combustion gas within the downstream zone, and eecting about 50% to 15% combustion to the extent of substantially all the available combustion-supporting oxygen content of -the mixed gases within the downstream zone by moving the mixed gases therethrough in amounts and under heat balance conditions sufficient to insure a temperature of the mixed gases of about 900 to 1200 C. and to at the same time endothermically convert saturated hydrocarbons of the mixed gases into unsaturated aliphatic hydrocarbons.

18. A method of endothermically producing unsaturated aliphatic hydrocarbons and essentially acetylene from gases containing saturated reaction hydrocarbons of the methane series withina pair of connected and enclosed zones one of which is termed an upstream zone and the other of which is termed a downstream zone, the steps of introducing a combustion gas mixture having at least a portion of its content preheated and containing a hydrocarbon gas and an available combustion-supporting oxygen-containing gas in substantially stoichiometric amounts into the upstream zone, burning the combustion gas within the upstream zone at a temperature of about 15002000 C., moving the gas therethrough in amounts and at a velocity and under heat balance conditionsV such that 50% to 85% of the combustible content of the' gas will be burnt, continuing to burn the combustion gas while introducing it into the downstream zone, introducing saturated reaction hydrocarbons directly into the downstream zone and into admixture with the combustion gas therein in amounts of about 1 part of the reaction hydrocarbons to about '1-10 parts by volume of the combustion gas, and burning the admixed gases within the downstream zone at a temperature of about 900 to 1200 C. by moving the admixed gases therethrough in -amounts and under heat balance conditions sumcient to insure 50% to 15% additional combustion of the original combustible content of the combustion gas and to at the same time endothermically convert saturated hydrocarbons of the admixed gases into unsaturated -aliphatic hydrocarbons.

-19. A method of endothermically producing unsaturated aliphatic hydrocarbons and essentially acetylene from gases having a relatively high percentage of saturated reaction hydrocarbons of the methane series within a pair of connected and enclosed zones, one of which is termed an upstream zone and the other of which is termed a downstreamv zone, the steps of introducing a combustion gas mixture of hydrocarbon gas and an available combustion-supporting oxygen-containing gas into the upstream zone, eecting combustion of the combustion gas within the upstream zone by moving the gas therethrough in vamounts and at a velocity and under heat balance conditions such that a portion of the available combustion-supporting oxygencontaining gas is burnt, continuing to burn the combustion gas while introducing it into the downstream zone at a temperature of about 1700" C., introducing reaction hydrocarbons directly into the downstream zone and into admixvture with the combustion gas of about 1700 C.

therein under conditions such that the resultant gas mixture has a temperature within a range of about 900 to 1200 C., the admixed gases being moved through the downstream zone in amounts and under heat balance conditionsv suillcient to insure a maximum endothermic conversion of saturated hydrocarbons of the mixed gases into unsaturated aliphatic hydrocarbons, and continuing and substantially completing combustion of the available combustion-supporting oxygen-containing gas content in the downstream zone.

20. A method as defined in claim 19, wherein 50% to 85% combustion is effected in the upstream zone.

21. A method of endothermically producing unsaturated aliphatic hydrocarbons and essentially acetylene from gases containing a relatively high percentage of saturated reaction hydrocarbons of the methane series within a pair of connected and enclosed zones one of which is termed an upstream zone and the other of which is termed a downstream zone, the steps of introducing a combustion gas mixture of hydrocarbon gas and an available combustion-supporting oxygen-containing gas into the upstream zone, effecting combustion of the combustion gas within the upstream zone at an elevated combustion-supporting temperature not in excess of about 2000 C. by moving the gas therethrough in amounts and at a velocity and under heat balance conditions such that a portion of the available gas will 18 be burnt. continuing to burn the combustion gas while introducing it into the downstream zone, and introducing reaction hydrocarbons directly into the downstream zone and into admixture with the combustion gas therein at a point where the temperature of the combustion gas is approximately 1700 C., the mixed gases within the downstream zone having substantially less than a stoichiometric amount of the combustion-supporting oxygen-containing gas, and the admixed gases being moved through the downstream zone in amounts and under heat balance conditions suicient to insure continued combustion within the downstream zone at a temperature of about 900 to 1200 C. and a substantial completion of combustion therein of the therein available combustion-supporting oxygen content of the mixed gases and to endothermically convert saturated hydrocarbons of the mixed gases into unsaturated aliphatic hydrocarbons.

22. A method as defined in claim 21, wherein the hydrocarbon gas of the combustion gas mixture is of essentially the same type of hydrocarbon as the reaction hydrocarbons that are introduced into the downstream zone.

23. A method as defined in claim 21, wherein the unsaturated aliphatic hydrocarbons comprise essentially acetylene, and the reaction hydrocarbons comprise essentially natural gas.

24. A method as defined in claim 23, wherein the combustible hydrocarbon gas comprises essentially natural gas. and the available combustion-supporting oxygen-containing gas comprises essentially air.

JOHN B. ORR, Jn.

REFERENCES CITED The following references are of record in the le of this patent:

` UNITED STATES PATENTS Number Name Date 1,730,440 Smith Oct. 8, 1929 1,773,002 Hunt Aug. 12, 1930 1,795,347 Reese May 10, 1931 2,012,092 Anderson Aug. 20, 1935 2,129,269 Furlong Sept. 6, 1938 2,274,249 Simpson Feb. 24, 1942 Certificate of Correction PatentNo. 2,498,444 February 21, 1950 JOHN B. ORR, Jn. A

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 8, for the Word later read lateral; column 8, line 37, for features read feature; column 11, line 71, for cobustion read combustion; column 13, line 9, for in, second occurrence, read is; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the'Patent Oce.

Signed and sealed this 23rd day of May, A. D. 1950.

l [mL] THOMAS F. MURPHY,

Assistant ommzasz'oner of Patents. 

1. A METHOD OF ENDOTHERMICALLY PRODUCING UNSATURATED ALIPHATIC HYDROCARBONS FROM GASES CONTAINING SATURATED REACTION HYDROCARBONS OF THE METHANE SERIES WHICH COMPRISES, THE STEPS OF EFFECTING COMBUSTION OF A COMBUSTIBLE GAS MIXTURE OF A COMBUSTIBLE HYDROGEN-CONTAINING GAS AND A COMBUSTION-SUPPORTING OXYGEN-CONTAINING GAS AT AN ELEVATED COMBUSTION-SUPPORTING TEMPERATURE OF NOT IN EXCESS OF 2000*C., IN SUCH A MANNER THAT AT LEAST A PORTION OF THE COMBUSTIBLE GAS MIXTURE IS BURNT AND WHILE SEGREGATING THE COMBUSTIBLE GAS MIXTURE FROM THE SURROUNDING ATMOSPHERE AND MOVING IT AS A CONTINUOUS STREAM; INTRODUCING REACTION GAS DIRECTLY INTO ADMIXTURE WITH THE COMBUSTIBLE GAS MIXTURE DOWNSTREAM THEREOF, THE ADMIXED GASES HAVE SUBSTANTIALLY LESS THAN A STOICHIOMETRIC AMOUNT OF AVAILABLE COMBUSTIONSUPPORTING OXYGEN, AND MOVING THE ADMIXED GASES UNDER CONDITIONS SUCH AS TO INSURE A CONTINUED AND SUBSTANTIAL COMPLETION OF COMBUSTION OF THE THEREIN AVAILABLE OXYGEN CONTENT OF THE ADMIXED GASES AND UNDER CONDITIONS SUCH AS TO PROVIDE AN ELEVATED COMBUSTION-SUPPORTING TEMPERATURE BELOW THAT OF THE COMBUSTION-SUPPORTING TEMPERATURE OF THE COMBUSTIBLE GAS MIXTURE BEFORE THE REACTION HYDROCARBONS ARE INTRODUCED THERETO AND TO PROVIDE AN IMPROVED YIELD OF UNSATURATED ALIPHATIC HYDROCARBONS, WHILE SEGREGATING THE ADMIXED GASES FROM THE SURROUNDING ATMOSPHERE AND CONVERTING SATURATED HYDROCARBONS OF THE ADMIXED GASES INTO UNSATURATED ALIPHATIC HYDROCARBONS. 